This core centralizes the pathology resources for all of the projects of the PPG. This results in cost savings, increased quality control and maximal comparability between the results of the projects. Importantly, new stains and methods are developed as required by novel findings that evolve in individual Project. These new stains and methods are then provided to every Project in a unified manner. Key aims of the Core are to provide: 1) expert advise in immunohistological aspects of experimental design to optimize results; 2) uniform histochemical and immunohistochemical staining of tissue sections; 3) pathological interpretation of tissue sections; 4) documentation of the pathology by high quality digital microscopic photography; 5) preparation of figures for manuscripts; 6) software for quantitative image analysis; 7) develop and evaluate additional reagents for new targets in response to novel findings In addition, this Core is responsible for ordering, quality assurance and control studies of all antibodies and reagents for use in the pathology methods. New reagents are developed and evaluated as requested by investigators in the 3 projects. Histopathology is central to all 3 projects. Each animal model is designed to answer clinically relevant questions. To that end, every transplant is evaluated relative to the Banff criteria for antibody mediated rejection (AMR).